Trouble with convolution and system response to inputs

AI Thread Summary
The discussion revolves around finding the system response to an input x(t) using convolution with the impulse response h(t). The user initially approached the problem graphically, reversing and shifting the input function to analyze the overlap with the impulse response. They calculated the convolution for various intervals, identifying the equations for the overlapping regions. Ultimately, they realized a mistake in their interpretation of the shift, correcting it to indicate a rightward shift rather than an upward shift. The user successfully solved the problem after clarifying their approach.
Lolsauce
Messages
21
Reaction score
0

Homework Statement



x(t) is input, h(t) is the impulse response, y(t) is output

Find the system response to the input x(t)

x(t): [PLAIN]http://img10.imageshack.us/img10/5157/55570988.jpg

h(t): [PLAIN]http://img593.imageshack.us/img593/1079/52492104.jpg

Homework Equations



Now I know the convolution integral is (f*g)(t) = [URL]http://upload.wikimedia.org/math/d/1/2/d122f80c065a111d4617fb3afdae0e53.png[/URL]

But for this problem I took a more graphical approach

The Attempt at a Solution



I changed the variable to T (Tau) and chose a function to be time reversed

So I took the input and shifted then reversed the graph giving me this:
[PLAIN]http://img13.imageshack.us/img13/8581/xtshiftandreverse.jpg

Afterwards I found t in which the graphs starts overlapping and not overlapping. I found at for t < -1, convolution c(t) = 0. So for my first intervals I looked at -1 < t < 0, which overlapping begins.

[PLAIN]http://img703.imageshack.us/img703/5655/widthj.jpg

This gives me a width of (t-2) - (-3) = t + 1 which should be the equation from -1<t<0.

I repeat the same process from 0 < t < 5, and this give me an obviously overlap and convolution of c(t) = 1.

Then for the overlap starts to leave, I get and equation of:
(t-3) - 3 = t - 6, this is from the endpoint of x(t-T) leaving h(t).

So at the end I get this graph, it seems kind of whack. Especially the first interval of -1 < t < 0. Can anyone give me some tips or see a mistake I've done.

[PLAIN]http://img69.imageshack.us/img69/7213/convolution.jpg
 
Last edited by a moderator:
Physics news on Phys.org
Nevermind, I just solved it, lolsauce. I turns from -1 < t < 0 the equation is t + 1, means it is shift to the right by one, NOT shifted up like I had thought.
 
Back
Top